A liquid crystal display uses a backlight to illuminate liquid crystal cells. Conventionally, backlight design varies according to the type of liquid crystal display, and edge light backlights have been employed for relatively small liquid crystal monitors, while direct backlights have been adopted for relatively large LCD televisions. As a reflective film for such backlights, a porous white film formed with air bubbles is generally used (Japanese Unexamined Patent Publication No. HEI-8-262208). In this regard, a white film deposited with an ultraviolet absorbing layer aimed at preventing yellowish discoloration due to an exposure to ultraviolet light emitted by a cold cathode fluorescent lamp has been proposed (Japanese Unexamined Patent Publication No. 2002-90515). Reflective films in which a layer containing soft beads is deposited on a base layer have also been developed as products particularly suited to use with a prism-shaped light guide plate (Japanese Unexamined Patent Publication No. 2003-92018 and Published Japanese Translation of PCT International Publication JP 2008-512719). Further, reflective films provided with a surface irregularity without the use of beads have been developed for use as reflective films for an edge light backlight (Japanese Unexamined Patent Publication Nos. HEI-9-197402 and 2001-266629).
In recent years, the slimline design trend of LCD televisions has led to the use of an edge light backlight in LCD televisions, and vigorous development efforts on edge light backlights are now underway. At the same time, the use of light emitting diodes (hereinafter abbreviated as “LEDs”) as low power-consumption mercury-free light sources is growing.
Unlike notebook computer displays and desktop monitors, televisions are required to provide high luminance, which makes it necessary to deploy a large number of LEDs. This, in turn, has necessitated the production of a chassis from aluminum, a highly heat-conductive material, as a means to efficiently dissipate heat. However, the use of aluminum tends to reduce mechanical strength, and this has given rise to a need to, for instance, give a corrugated shape to the rear chassis 4, as illustrated in FIG. 1, via a drawing process. Such a corrugated shape has also been designed to save space by housing circuitry, etc. in furrow sections for the sake of slimline design.
An edge light backlight requires a light guide plate as an essential optical element. With conventional notebook computers and desktop monitors, light guide plates of up to 25 inches in size are sufficient, but televisions require 30 to 60-inch ones. For this reason, various light guide plates have been developed, including light guide plates with surface convexes, typically an acrylic plate (3 to 4 mm in thickness) on which a circular or dot pattern has been printed, and light guide plates engraved concaves using the laser processing or UV transfer method. A technique to form light guide plates with surface convexes directly from resin pellets via injection molding has also been developed.
However, the development of large thin edge light backlights as described above is associated with some reflective film-related problems, particularly (i) to (v) below:                (i) Unevenness in luminance caused by uneven close contact between the light guide plate and reflective film.        (ii) Unevenness in luminance caused by the scraping of the light guide plate by bumps created in the reflective film by localized protrusions present in the rear chassis as a result of defective molding.        (iii) Unevenness in luminance caused by the scraping of the light guide plate due to friction between the light guide plate and the reflective film during the television vibration test.        (iv) White spotting (appearance of any visually observable bright spotty areas) caused by uneven close contact between the light guide plate and the reflective film as described in (i) above as a result of the convexes of the light guide plate pressing on the convexes formed on the reflective film, a problem specific to a backlight featuring a light guide plate with convexes.        (v) White spotting (appearance of any visually observable bright spotty area) caused by the crushing of convexes formed on the reflective film by the convexes of the light guide plate and attachment of the remains of those convexes to the light guide plate, a problem specific to a backlight featuring a light guide plate with convexes.        
The reflective films described in JP '018 and JP '719 have some effectiveness in improving the unevenness in luminance caused by the scraping of the light guide plate. However, those films are unable to fully satisfy the level of stiffness and maximum height of convexes required of the LCD television application, which is in the middle of a trend towards slimline design and large size.
It could therefore be helpful to provide a white reflective film capable of improving the luminance and unevenness therein, avoiding uneven close contact with, and scraping of, the light guide plate, and minimizing the crushing of convexes formed on at least one side of it, even in cases where the reflective film is laid directly over a corrugated chassis designed to house circuitry, etc. or the reflective film is used in combination with LEDs.